Morphometric analyses of the electric organ of Torpedo: the influence of different fixative modes on the vesicle diameter.

The influences of various fixatives on the vesicle size of the electric organ of Torpedo marmorate were investigated. Thin section and freeze etched preparations were examined under the electron microscope. In thin section increased vesicle diameters were observed compared with the freeze etched preparations. The same experiments in different torpedo fish led to significantly different vesicle sizes observed. Variations of the molarity, the pH and osmolarities result in particularly high differences in vesicle diameters. Using Karnovsky's method (1965) and a fixative consisting of 2.5% glutaraldehyde in 0.2 M cacodylate buffer, pH 7.2, results in vesicle sizes comparable to those reported by other authors. Results obtained from freeze etched preparations are not comparable in general with results from thin section experiments with the same fixative.